Steady-state mRNA and protein up-regulation levels of Fst expression upon incubation of C2C12 cells with 1,25-D3. Cultures of C2C12 cells were incubated as in Fig. 1 for 4 and 7 d. Total RNA and whole-protein extracts were isolated for qRT-PCR and Western blottings. VD1 and VD2 are different pools of two samples each. Mean ± sem corresponds to experiments done in triplicate; **, P < 0.01 and ***, P < 0.001. A, Cells incubated or not with 1,25-D3 for 1 d. B, Cells incubated or not with 1,25-D3 for 4 d. VD, Vitamin treated cells whole extracts; C, control cells, non-incubated with 1,25-D3. C1 and C2 correspond to different pools of two samples each.